2 Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com>
5 #include <util/delay.h>
10 #define WAIT(stat, us, err) do { \
11 if (!wait_##stat(us)) { \
12 ibm4704_error = err; \
18 uint8_t ibm4704_error = 0;
21 void ibm4704_init(void)
26 uint8_t ibm4704_send(uint8_t data)
28 bool parity = true; // odd parity
35 /* wait for Start bit(Clock:lo/Data:hi) */
36 WAIT(data_hi, 300, 0x30);
39 for (uint8_t i = 0; i < 8; i++) {
40 WAIT(clock_hi, 100, 0x40+i);
48 WAIT(clock_lo, 100, 0x48+i);
52 WAIT(clock_hi, 100, 0x34);
53 if (parity) { data_hi(); } else { data_lo(); }
54 WAIT(clock_lo, 100, 0x35);
57 WAIT(clock_hi, 100, 0x34);
61 WAIT(data_lo, 100, 0x36);
64 _delay_us(200); // wait to recover clock to hi
68 if (ibm4704_error >= 0x30) {
69 xprintf("x%02X ", ibm4704_error);
71 _delay_us(200); // wait to recover clock to hi
75 /* receive data when host want else inhibit communication */
76 uint8_t ibm4704_recv_response(void)
78 // 250 * 100us(wait start bit in ibm4704_recv)
82 data = ibm4704_recv();
83 } while (try-- && ibm4704_error);
89 Clock ~~~~___~~_~~_~~_~~_~~_~~_~~_~~_~~_~~~~~~~~ H:60us/L:30us
91 Data ____~~X==X==X==X==X==X==X==X==X==X________
92 | 0 1 2 3 4 5 6 7 P(odd)
96 uint8_t ibm4704_recv(void)
99 bool parity = true; // odd parity
100 ibm4704_error = IBM4704_ERR_NONE;
103 _delay_us(5); // wait for line settles
106 WAIT(clock_lo, 100, 0x11); // wait for keyboard to send
107 WAIT(data_hi, 100, 0x12); // can be delayed that long
109 WAIT(clock_hi, 100, 0x13); // first rising edge which can take longer
111 for (uint8_t i = 0; i < 8; i++) {
112 WAIT(clock_hi, 100, 0x20+i);
118 WAIT(clock_lo, 150, 0x28+i);
122 WAIT(clock_hi, 100, 0x17);
123 if (data_in() != parity) {
124 ibm4704_error = IBM4704_ERR_PARITY;
127 WAIT(clock_lo, 150, 0x18);
130 WAIT(clock_hi, 100, 0x19);
131 WAIT(data_lo, 1, 0x19);
134 _delay_us(200); // wait to recover clock to hi
137 if (ibm4704_error > 0x12) {
138 xprintf("x%02X ", ibm4704_error);
141 _delay_us(200); // wait to recover clock to hi